Rectifier system.



S W. FARNSWORTH.

RECTIFIER SYSTEM. APPLICATION FILED FEB- 5, i914.

Patehied Aug. '7, 191'? INVENTOR ,L/% W2/Z ATTORNEY WITNESSES:

UNITED STATES PATENT our 1on1 SIDNEY W. FABNSWOBTH, OF PITTSBURGH,PENNSYLVANIA, ASSIGNOR TO WESTING- HOUSE ELECTRIC AND MANUFACTURINGCOMPANY, A. CORPORATION OF'PENNSYL- VANIA.

RECTIFIER SYSTEM.

Specification of Letters Patent.

Patented Aug. 7, 1917.

To all whom it may concern:

Be it known that I, SIDNEY W. FAnns- WORTH, a citizen of the UnitedStates, and a resident of Pittsburgh, in the county of Allegheny andState of Pennsylvania, have invented a new and useful Improvement inRectifier Systems, of which the following is a specification.

My invention relates to systems for contifier, and theluni-directionalcurrent pro ceeding' from the rectifier is supplied to a load. If thesourceof alternating current is the secondary winding of a transformer,it is usual to supply current to the rectifier anodes from the endterminals of the transformer secondary, and to provide a connection fromthe direct current load to the middle point of the transformer. Withsuch an arrangement, the anodes of the rectifier must have sufiicientnegative resistance to withstand the full voltage strain of thetransformer, and if the negative resistance breaks down, a short circuitwill occur between the anodes, which will be a direct short circuit onthe transformer winding. The resulting current will be limited only bythe reactance of the transformer, the resistance of the leads and theresistance'of the vapor gap between the anodes. Such current is verylarge and may be as much as twenty times the normal current taken by therec- 4b tifier under normal full load.

I have improved this arrangement and greatly reduced the current whichthe anodes must ca'rryin case of short circuiting by placing the load inthe anode leads. If

' the load is such as is found in electrolytic industries, the voltagestrain which the anodes are called upon to stand may be reduced toscarcely more than half the strain .to which the anodes are subjected inthe ordinary systems. Moreover, the "current which can flow in case ofshort circuiting between the anodes, is very much less than the normalfull load current, being limited by the resistance of the load.

The single figure of the accompanying drawing is a diagrammatic viewshowing one system of connections embodying my in vention. I

In the drawing, a rectifier 1 is supplied with current from analternating current source which, asshown, is the secondary Winding 2 ofa transformer. Leads 3 and 4 connect the terminal points of thetransformer to anodes 5 and dot the rectifier 1. The rectifier isprovided with a vaporizable cathode 7 which may be of mercury, and alead 8 connects the cathode to the middle point 10 of the transformerwinding. One or more auxiliary keeping-alive electrodes 9 may also beprovided. Loads l1 and 12 are connected in series in the leads 3 and 4and these loads are represented as batteries of electrolytic cells,although my system may be used with any load which is adapted to receivepulsating uni-directional current. The batteries of cells used in theelectrolytic industries are especially well adapted for my use becausethe current delivered to the loads, in my system, is intermittent andpulsating, being active only during alternate half-cycles of thealternating current supply. Such batteries require exceedingly largecurrents, which it is sometimes difficult to supply, even with largerotary converters, and such service is therefore especially severe forrectifiers, as usually connectcd. My invention, however, makes itentirely possible to use vapor 'rectifiers in this service, since bothconnections are equally well suited to the operation of the batteries.

It will be observed that the current from ,the transformerpasses firstthrough the loads 11 and 12, then to theanodes 5 and 6, then to thecathode 7 and thence back to the middle point 10 of the transformerwinding.

In case the negative resistance of one of the anodes 5 and 6 isdestroyed, a short circuit will form between them, and the cur rent willreturn to the transformer directly through the anode load. However, thecurrent across the anodes, under such circum-

